1. Field of the Invention
The present invention relates to a marine vessel propulsion device that includes a shift mechanism unit. The shift mechanism unit is configured to switch between a transmitting state, in which a driving force of an engine is transmitted to a thrust generating unit, and a cut-off state, in which the driving force of the engine is cut off from the thrust generating unit. The present invention also relates to a marine vessel that includes such a marine vessel propulsion device.
2. Description of the Related Art
An outboard motor is one example of a marine vessel propulsion device. An outboard motor according to one prior art is disclosed in Japanese Unexamined Patent Application publication No. 2005-113904. This outboard motor includes a shift mechanism unit. The shift mechanism unit is capable of switching between a transmitting state, in which a driving force of an engine is transmitted to a propeller (thrust generating unit), and a cut-off state, in which the driving force of the engine is cut off from the propeller.
In the outboard motor of the prior art, a drive shaft is coupled to a crankshaft of the engine. The propeller is fixed to a propeller shaft. A mechanical forward-reverse switching mechanism (shift mechanism unit) is disposed between the drive shaft and the propeller shaft. A shift operation lever (shift operational unit), which is operable by a user, is disposed on a hull. The forward-reverse switching mechanism is mechanically connected to the shift operation lever. The forward-reverse switching mechanism is configured to switch between the transmitting state (forward drive or reverse drive) and the cut-off state (neutral) in connection with the operation of the shift operation lever.
An operation, in which the user moves the shift operation lever from the forward drive or reverse drive position to the neutral position, is referred to as a “shift-out operation.” With the prior art, in the shift-out operation, misfire control of a spark plug (ignition unit) of the engine is executed as early as possible after detection of the shift-out operation. An engine speed is thereby decreased, and this is intended to lighten a load applied to the shift operation lever.
An electronic shift drive mechanism with a drive-by-wire (DBW) system has been proposed. With a DBW system, the shift operation lever and the forward-reverse switching mechanism are not connected mechanically. An electronic control unit receives position information on the shift operation lever and controls a shift drive unit, such as a shift drive motor, etc., based on the received data. The state of the shift mechanism unit is switched by the shift mechanism unit being driven by the shift drive unit.